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Re: [PATCH 3/3] MIPS: DMA: Add plat_extra_sync_for_cpu()

To: David Daney <ddaney@caviumnetworks.com>
Subject: Re: [PATCH 3/3] MIPS: DMA: Add plat_extra_sync_for_cpu()
From: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Date: Thu, 9 Sep 2010 19:34:27 +0200
Cc: Kevin Cernekee <cernekee@gmail.com>, Ralf Baechle <ralf@linux-mips.org>, linux-mips@linux-mips.org, linux-kernel@vger.kernel.org
In-reply-to: <4C8914E8.5030002@caviumnetworks.com>
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On Thu, Sep 09, 2010 at 10:10:00AM -0700, David Daney wrote:
> On 09/08/2010 04:02 PM, Kevin Cernekee wrote:
>> On noncoherent processors with a readahead cache, an extra platform-
>> specific invalidation is required during the dma_sync_*_for_cpu()
>> operations to keep drivers from seeing stale prefetched data.
>
> But as far as I can see, none of your plat_extra_sync_for_cpu() do anything.
>
> Perhaps adding this hook should be deferred until there is actually a user.

looks like this is doing what the non_coherent_r10000 case does. So IMHO
either which make non_coheren check more generic or could use the new
plat_sync thingie for IP28 and other non coherent r10k boxes.

Thomas.

-- 
Crap can work. Given enough thrust pigs will fly, but it's not necessary a
good idea.                                                [ RFC1925, 2.3 ]

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